Method of obtaining solutions or quasi solutions of certain metallic oxids.



PATENT onnion.

zncrihmn'n cnarwnlrenr, or rnronn, ENGLAND.

METHOD or OBTAINING- sonurroiis oza .eUAsr'soLUrIonsoF onnrnln METALLIC'1 'oxIDs. I

{$3,692, Specification of Letters Patent. -Patented'Apr. 4t, 1911. NoDrawing. Applicationflled June 29, 1909.1 Serial No. 505,045. 1 I

'To'ail whom it may concern:

Be it known 'that I, ZACHARIAH GART- WRIGHT, a subjectof the King-ofGreat Britain, and resident of Ilford,-iEssex, England, have invented aMethod of Obtaining Solutions or Quasi Solutions of Certain MetallicOxids, ofwhieh the following is a specification.

This application i use to v a" method robtaining solutions" or Iquasisolutions of oxids of metals contained in the iron -gr'oup,

viz., iron, manganese, and chromium which are insoluble in water i andother -media chemically indifi'erent to said oxids.

In a separate a lioati'n filed" January 12, 1910, bearing gerial No.537,763, e111 titled 'Method of obtaining solutions or.

quasi-solutions of certain metallieoxids, I"

have set forth a novel rocess .of treating metallic oxi s,'notably t oseof metal Icon-v tained in the; iron series, viz: iron, manganese,chromium, which are insoluble-in water and other media chemicallyindifi'erentto the said oxids, and in Which-alkali the purpose ofobtalmng what isvirtu'ally a soluble form'of certain of these oxids in achemicall inert medium.

According to the method forming the sub- 1 ject of the presentapplication, the "metallic oxids are suspended man aqueous solutionof asaponaceous material and thereafter prggipitated by the addition of anacid.

convenience I refer tothe mixture' ofox'id and the saponaceous'menstruumas a solution I mean toimply not that it is a-gsolution'in the strictsense of the term, but' that it is a mixture so intimatethat itsconstitus ent elements will pass through filter paper together withtheso'luble fatty acidsfwith- I out separation. Similarly, the; solu- 1Me? as applied to the oxids isfnot to be understood n 113 strictsense,lbut in; the

sense corresponding to the abovejdefinition.

Although the novel menstruum I employ may, broadly speaking, be said toconsist -of Too great an excess of alkali must be avoid;

ed, otherwise more or less rapid precipitais employed asltheprecipitating .agent, foran extremely dilute aqueous solution offsoap,

tion of the oxids ensues. A certain proportion of unsaponified fatsor'glycerm may be present in the soap solution without detriment to theprocess.

[In the manufacture of mottled soap,

point is reached corresponding to a concentration of about 5% of soapymatter beyond which further-dilution with water results in a decrease inthe rapidity of precipitation.-

- The increase in what, as above stated, may, for convenience sake, becalled the solubility ofthe oxid, consequent on further dilution is veryrapid, a maximum being reachedkbetween, the limits of l and 0.5%concentration. If the soap solutiong be of r 1% concentration,precipitationof the oxid practically ceases, z'; e. ,the oxid willremain suspended in, or; distributed throughout, the soap solution for apractically unlimited period without any perceptible tendency to p v ibecome deposited under the action of gravity. to be understood thatalthough in the following description for the'sake of The above ap liesto other oxids besides those of iron," or instance, those ofchromium'and manganese. It is, however, only thehydrated oxids which aresoluble (usm'g this term in-the-sense above indicated), thesO-calledsolubility increasing with the de- -gre'e of hydration specific gravityevidently being 'thejdetermining factor. color of these oxids alsodepends upon their ,hydration (the color -passing thr0ugh pr( gressivelydarker shades when an oxld v1s by employing a menstruum of a givenpredetermined strength certain one or more lighter (and consequentlymore brlghtly colored) oxids can be separated from the heavier e;darker) ones byvirtue of-theselective solvent action exercised upon them"by the'menstruum. I have therefore, discovered a novel menstruum oriron and certain other oxids, which, for many purposes, may-be regardedpractically as water, conit. is well known that if iron oxid beemitself, experiment showingthat a critical Since the dehydrated byignition) it will be seen that,

sisting as it does of an extremely .dilute aqueous solution of thecomparatively inert substance soap, and being therefore a very lnnocuousvehicle or medlum 'fo'rconveying the oxid. 'Itwill be evidentthat by theuse:

of this menstruum these bodies may be applied to many purposes to whichthey were ture;

hitherto, -in.-the absence of such a menstruum,

inapplicable. From this solution the oxids are easily precipitatedby'the'addition of asmall ,quantity of-an acid, the oxids being thenprecipitated with the fatty acid with" which they were associated.Theipresence' of the fatty aeids, if 'of a dryin oil, in the recipitateobtained, is not disa vantageou's or many purposes, such as colormanufac- .percentage of combined water) or of manroceed as ganese, or ofchromium, I may follows: I suspend thefinely. levlgated impure oxid inthe prepared menstruum with mechamcal stirring.

menstruum may be anything between the' The strength of the limits, say,of 5 to 0.5%.

The mixture obtained as above is allowed to stand, whereupon theimpurities, both those such assilica associated with the'oxidand thosein the water, will precipitate.

' Too much oxid should, of course, not be introduced into the solution,5. e. not so much as to appreciably affect the fluidity of the mixtune,otherwise satisfactory separation will not be obtained. I find 7% ofoxid' to be about the maximum for good results. As

soon as this preciptation has ceased the so 'lution, containing the oxidand a certain amount of the more soluble impurities, is decanted offinto another vessel, anda small quantity of acid is then added to it,whereupon precipitation of the oxid (or more strictly speaking, themixture of oxid and fatty acids) at oncemomrnences. The liquid is thenrun olf andthe precipitate-washed.

The above operations may be repeated if desired, successive operationsyielding a purer-or more finely divided precipitate of oxid. The aboveconstitutes a ready and inexpensive method of purifying metallic oxidsto be employed in the manufacture of paint and the like.

In order to illustrate what the strengths of the menstruum mean, Iwilldescribe what I mean by, say, a 1% menstruum; Dissolve one pound ofcaustic soda or caustic potash in about eight pounds 'ofwater, then takeone pound of rosin,.- grease, or oil and Warm it until liquid, then pourit slowly into the alkali solution, stir u until well mixed and allow tostand for a out seven days, after which boil up and add slowly furtherwater until a quite clear solution is obtained in 198 pounds of Myinvention finds its most importaht as plication in the partial searatlon (accor ing to color) of mixed oxlds from one another, withthe-ultimate object of applying them as pigments to the manufacture ofpaint-s and the like. Although forithe reasons hereinafterspecified, itis nghpract cable,. according to the process, thei'subject of myinvention, to absolutely. separate any required oxid fromthoseotherswithwinch it is associated (and whichmay' differ from it either according.tothe nature' of the water. This I call-a 1%- solution.

metals concernedor in their respectiveper centages of combined water) soas to obtain a slngle pure oxid of defin te composltlon, neverthelessth1s 1s of small consequence,

the object in view being simply the 'assorta-- tion of the oxidsaccording to shade so as suitable for the manufacture of paints.-

The process may be described as an empirical one, the problem belngtoobtaln to obtain samples of the brightest shades from any given specimenof mixed oxids, a. sample or series of samples of mixed OXlClS of anyrequired shade (the shade being determined by the varying prepo deranceof the lighter and darker oxids while the method. adopted dependsupon/ithe fact that from a solution of the mixed oxids precipi-- tat-ionof the different oxids present takes place in the order of theirrespective specific gravities. By this I do not mean sim- IOt ply thatprecipitation of all the oxids pres-.

ent goes on simultaneously, only with varying rapidity, but that for agiven predetermlned strength of the menstruum, certain oxids will bethrown down and other Wlll. remain behind in solution. As a matter offact, however, rapidity of precipitation does play an important part inthe actlon, that is to say there. is no sharply defined limitdetermining precipitationfof one oxid only or alternatively of that oxidand also the being that as a given limit is approached not only does therapidity of precipitatlon of the heavier oxid increase, but the next inorder of gravity also commences to precipitate until when the limit isactually reached both oxids are precipitated with practically equalrapidities. Hence it will be seen that by the application of thisprinciple it-ls possible to obtain, from a given specimen of mixedoxids, an infinite number. of samplcs containing progressivelyincreasing proportions of an .oxid of any given specific gravity. Sincethe color of these oxids is darker according as the specific gravity andpercentage of combined water is higher, it will be evident thatany shademaybe obtained within the range ofcolors presented by the oxidsdealtwith. y In the case of iron 13 next in order of specific gravity, thereality and man anese, however, the specific gravities of oxidscontaining corresponding percentages of oxygen and of combined water donot permit of complete separation by the application of this method.

In carrying out the assortation process I proceed as follows :Suppose itis required to preparea sample of mixed oxids ,ofian.

orange-yellow shade. This shade will, of course, correspond with acertain high percentage of the lighter oxids, the numerical value ofthis percentage being, however, of"

no immediate consequence. The object is to obtain a menstruum of suchstrength as will dissolve the oxid of lighter color and that proportionof the darker oxids, the presence of Whichis necessary to impart theshade required to the mixture of oxid dissolved. When a solution of therequired example, the process is worked by progressive solution. Thedetails of the process are as follows :I first prepare a menstruum ofsufiicient strength to dissolve all the oxids contained in the specimento be treated. This menstruum (which I will re-' for to as the standardsolution) may be of a strength, say of 2%, the precise meaning whichthis strength implies having been above explained. From this standardsolution I then prepare a small quantity of a solution of a strengthinsu'flicient to dissolve any of the oxids, and thereafter increase itsstrength until it is found to hold such of the oxids in solution as willgive the shade required. VVhen a test solutionof the required strengthhas been obtained, its strength can be easily calculated from theproportions of water and standardsolution employed. A quantity of themenstruum of the required strength can then be prepared for the purposeof obtaining .a pigment of the required shade from the specimen ofcommercial oxid submitted. All that is. nec- -essary is to decant offthe solution of color and to thereafter precipitate it with acid,

care being taken that only the requisite quantity of precipitant isemployed.

Owing to the fact that no two specimens of commercial oxid can ever berelied upon to possess 'the same uniform composition, and that moreoverno satisfactory method is known of determining such percentagecomposition, it will be foundnecessary always to proceed in the abovemanner by 'operating first with a test solution. Further more, since theforegoing remarks apply with equal force to the soap supplied incommerce e; the percentage of fatty acids and alkali obtainable insolution from any given specimen of soap being indefinite) and moreover,the hardness of the water employed being also a factor which must betaken into consideration, I find it necessary to prepare the soapsolution according to the special process above described.

If it be desired to prepare a permanent solution of 'an oxid, it is onlynecessary to employ a menstruurfi of the maximum solvent power. By this.means the insoluble impurities areat once precipitated, whereupon thesolution of metallic oxid may then be decanted OH and be preservedindefinitely.

To obviate the consequences of such an excess of alkali in the menstruumas would causegradual precipitation, advantage may be taken of the factthat certain organic sub; stances, such as sugar, tend to prevent theprecipitation of ferric oxid 'by alkalies.

I claiml.' A method of separating certain metal-- lic oxids, consistingin placing the said oxids in an aqueous solution having not less than0.5% of a saponaceous material; then increasing the percentage to obtainthe desired color; then precipitating the oxids in said solution by theaddition of an acid; and then decanting the liquid.

2. A method of separating certain metal lic oxids, consisting in placingmetallic OX- ids in an aqueous solution containing not more than 5% of asaponaceous" material; then precipitating the said oxids out of saidsolution by the addition thereto of an ac1d; and then decanting theliquid.

ZACHARIAH oAarvvmcrmr.

Witnesses:

EDWIN GEORGE W ITE, Rose ISABEL PAGE.

